This application relates to decorative heat transfers or decalcomania, and more particularly to heat transfers far providing a decorative metal film pattern.
Metal foil decorations have been applied by hot stamping techniques to plastics, paper and other relatively soft embossable surfaces, have good brilliance, and are in substantial use. However, hot stamping has not been generally applicable to hard or rigid surfaces such as glass, metal, ceramics, some thermoset plastics, and the like. Hot stamping also requires a stamping die and a relatively long dwell time for transfer which limits the production rates obtainable. Also, hot stamping foils have not normally included descriptive or decorative ink designs printed to be exposed after transfer.
Discrete, pre-printed heat transfers comprising ink designs, often in multiple colors printed sequentially in register, are known and are also in substantial use. Examples of such discrete, pre-printed transfers are shown for example, in U.S. Pat. Nos. 2,862,832; 2,989,413 and 2,990,331. Equipment for applying such decorations to a receiving surface is disclosed in U.S. Pat. Nos. 3,064,714 and 3,231,948. Such transfers can be pre-heated to or near transfer temperature and much shorter dwell times are required, as little as 25 milliseconds being sufficient, permitting relatively high production rates. Decorative ink designs are inherent. Such discrete transfers can also be applied to rigid surfaces such as glass, ceramics, metal and the like.
Discrete, pre-printed heat transfers have not incorporated metal foil patterns because it has not been feasible to vacuum deposit metal in a pattern and the moisture in the commonly employed paper carriers causes difficulties in deposition. Therefore metal has been avoided or its effect simulated with pigmented inks which lack the attractiveness and appearance of foil.
It has been proposed in U.S. Pat. No. 3,463,651 to print an ink design on the release surface of a plastic film, then to vacuum metalize the entire release surface, followed by overcoating with an adhesive. However by this procedure it is not possible to provide metal in a pattern on the decal, paper cannot be used as a backing, and a transfer die is required. Also the carrier web must be removed from the press for metallizing and thereafter remounted for coating the adhesive.